This invention relates to an exposure method and an exposure apparatus used to transfer a mask pattern onto a substrate in a lithography process to manufacture microdevices, such as semiconductor elements, image-capture elements (CCDs and similar), liquid crystal display elements, and thin film magnetic heads, and in particular a method and an apparatus suitable for use in an exposure apparatus comprising a mechanism to focus the image plane of a projection optical system on the substrate surface by an automatic focusing method. More specifically, this invention concerns an exposure apparatus comprising a mechanism to control the temperature of prescribed members.
With the advanced integration of semiconductor devices in recent years, steppers and other projection exposure apparatuses are required to project images of circuit patterns with fine line widths, with high resolution, onto a wafer (or glass plate or similar) covered with resist as the substrate in each shot area. To this end, the numerical aperture of the projection optical system must be increased, and the exposure wavelength must be shortened; however, this is accompanied by a tendency toward reduction of the focal depth of the projection optical system. Thus the need arises to increase the focusing accuracy of the automatic focusing mechanism comprised by a projection exposure apparatus, in order to perform exposure in which the wafer surface is accurately adjusted within the range of the reduced focal depth, with respect to the image plane of the projection optical system (the best focus position of the projected image of the mask or reticle pattern).
This automatic focusing mechanism comprises an auto-focus sensor (hereafter xe2x80x9cAF sensorxe2x80x9d) which detects the focus position on the wafer surface (the position in the optical axis direction of the projection optical system), and a stage system which controls the height of the wafer or reticle based on the measurement results of this AF sensor. As this AF sensor, conventionally an oblique-incidence AF sensor is used in which a slit image or similar is projected obliquely onto the surface for detection, without passing through the projection optical system, and light reflected from this surface for detection is detected, as disclosed for example in Japanese Patent Application Laid-open No.6-283403. While this oblique-incidence AF sensor has the advantage of enabling measurement of fluctuations in the focus position of the surface for detection even during exposure, measurement light does not pass through the projection optical system, so that if for example the position of the image plane of the projection optical system fluctuates due to the heat of irradiation of the illumination light (exposure light) used in exposure, it is difficult to directly measure the change in defocusing of the surface for detection.
In order to measure the defocusing amount of the surface for detection with respect to the actual image plane of the projection optical system, a TTR (through-the-reticle) AF sensor has been proposed which projects on the in wafer stage the image of a mark on the reticle through the projection optical system and measures the position of the image plane based on the contrast of this image, as disclosed for example in Japanese Patent Application Laid-open No. 9-283421. This TTR type AF sensor has the advantage of enabling direct measurement of the image plane of the projection optical system; but in order to perform this measurement, exposure of the wafer must be interrupted, and if the AF sensor is used too frequently, the throughput of the exposure process is lowered. Hence as one example of a conventional method, a TTR type AF sensor and an oblique-incidence AF sensor are combined; the oblique-incidence AF sensor is used for focusing during normal exposure, and the TTR type AF sensor is used to measure the position of the actual image plane for each lot, once every half-day, once a day, or with similar frequency; based on the measurement results, the values measured by the oblique-incidence AF sensor are calibrated.
In a conventional exposure method like that described above, by performing calibration of the oblique-incidence AP sensor at prescribed time intervals, for example, the focusing accuracy can be maintained within a prescribed tolerance without greatly lowering throughput. However, because an oblique-incidence AF sensor is positioned on one side of the projection optical system in the vicinity of the wafer, if the illumination heat of the exposure light causes the temperature of the wafer to gradually rise, the temperature of members comprised by the oblique-incidence AF sensor also rises, and gradual drifting of the measured focus position may occur. Further, slight irregular shifts in position of prescribed optical members comprised by the AF sensor may cause irregular drifting of measured values. Such drift amounts are minute; but if the exposure wavelength is made still shorter and the focal depth is further decreased in response to the still higher integration levels of future semiconductor devices, drift in the values measured by the oblique-incidence AF sensor may cause the wafer surface to deviate outside the range of the focal depth for the image plane.
In order to lessen the drift in values measured by such an AF sensor, the above-described TTR type AF sensor may be used to perform frequent calibration (for example, each time the wafer is changed); but if exposure is interrupted and the TTR type AF sensor is used with such high frequency, there is the problem that throughput is greatly reduced.
In order to transfer, at a prescribed magnification and with high fidelity, a reticle pattern for use as a mask onto a wafer (or glass plate or similar) covered with resist as a substrate, conventionally the principal parts of the exposure apparatus are housed on a box-shape chamber; dust removal from within this chamber is performed extensively, and air regulated at a nearly constant temperature is supplied.
In recent years, high-precision temperature control not only of the reticle and wafer, but of various optical systems in the exposure apparatus has been sought in order to accommodate the ever-finer details in semiconductor elements and similar. In order to improve the resolution of an exposure apparatus, the wavelength of the illumination light used in exposure (exposure light) has been shortened, from primarily the i-line of mercury lamps (wavelength 365 nm) to KrF excimer laser light (wavelength 248 nm), and then to ArF excimer laser light (wavelength 193 nm); hereafter the use of F2 laser light (wavelength 157 nm) and similar is also being studied. When the exposure wavelength is thus shortened, the transmissivity in ordinary air of the illumination light for exposure (exposure light) declines, and so recent an exposure apparatus comprises a gas supply mechanism to supply a gas having comparatively good transmissivity for the exposure light in part of the optical path of the exposure light.
FIG. 24 shows an exposure apparatus comprising such a gas supply mechanism; in this FIG. 24, exposure light emitted from the exposure light source 250 incorporating an excimer laser light source passes through the light transmission unit 268 including a relay optical system and through the optical path correction unit 252, and is incident on the exposure main unit. Exposure light incident on the exposure main unit passes through the illumination system 253 and illuminates the reticle 259, and a projected image passes through the projection optical system 264 and is projected onto the wafer 262. The wafer 262 is held on the wafer stage 261, and the wafer stage 261 is mounted in freely movable fashion on the wafer base 260; the projection optical system 264 is supported by the support member 263 of a column 257 embedded in the wafer base 260, and the reticle 259 is mounted on a reticle stage, not shown, on a reticle base 258 fixed in place on the column 257. A support member 255 supporting the illumination system 253 is fixed in place on the reticle base 258 via the column 256.
In order to control the overall temperature of the exposure apparatus at close to the target temperature, air controlled at a prescribed temperature is blown by a blower unit 266 for overall air conditioning within the chamber into the part 269, enclosed by the dotted line and containing the upper part of the projection optical system 264 and the reticle 259. At this time, far-ultraviolet light such as KrF excimer laser light (wavelength 248 nm) causes a chemical reaction with prescribed dust in the air to generate material which makes lenses cloud; because this dust is readily absorbed by ozone, it is desirable that the parts of the optical path in which illumination is high be filled either with dry air passed through a chemical filter, or with air from which ozone has been removed. Light in the vacuum ultraviolet range such as ArF excimer laser light (wavelength 193 nm), or light at wavelengths close to this, has high absorbance by oxygen, and so it is necessary that the principal parts of the optical path be supplied with nitrogen gas or similar in which the oxygen content has been reduced. In the exposure apparatus of FIG. 24, when for example ArF excimer laser light is used, the optical path within the part 268 enclosed by the dotted line from the blower unit 251 to the illumination system 253 is purged with nitrogen gas from the gas supply mechanism 267.
In the part 254 in particular, enclosed by the dotted line and containing the lower part of the projection optical system 264 and the wafer stage 261, highly accurate position measurements must be performed using a laser interferometer. In order to reduce fluctuations in the measurement beam in the optical path, air controlled at a prescribed temperature is supplied by the blower unit 265 of a partial air conditioning mechanism.
As described above, in conventional devices the exposure light source 250 containing the excimer laser light source is often supported separately from the exposure main unit and outside the chamber in which the exposure main unit (in FIG. 24, the members above the waver base 260, excluding the illumination system 253) is installed, from the standpoint of operational safety and of separating and positioning the exposure main unit away from sources of vibrations and heat insofar as possible. When the exposure main unit and exposure light source 250 are thus supported independently, corrections must be made for shifts in the optical axis of the exposure light caused by vibrations of the exposure light source 250 or other factors. Hence in the conventional device of FIG. 24, the optical system is separated before the illumination system 253 containing an attenuator unit or similar to attenuate the exposure light, and the optical axis correction unit 252 is used to correct for shifts in the optical axis between the light transmission unit 268 and the illumination system 253.
However, if the optical system is separated before the illumination system 253 in this way, nitrogen gas or some other gas easily leaks from the boundary between this illumination system 253 and the optical axis correction unit 252, so that the amount of gas supplied from the gas supply mechanism 267 is increased, and there is the problem that the operating costs of the exposure apparatus are increased. Also, because this gas leaks readily, air or other gases from outside may become intermixed within the illumination system 253 at or near the boundary, so that the transmissivity of the exposure light may be reduced.
The air blown from the blower unit 266 for overall air conditioning into the part 269 enclosing the reticle 259 is obstructed by the illumination system support member 255, reticle base 258, projection optical system support member 263, and the columns 256, 257 linked to these, so that the environs of the reticle 259 and the upper part of the projection optical system 264 may not be adequately air-conditioned. In particular, when there is inadequate air-conditioning in the environs of the reticle 259, the reticle temperature rises and the reticle expands, causing a problem in which a magnification error occurs in the pattern transferred onto the wafer.
In actuality, in the lower part of the projection optical system 264 are installed members of complex shapes such as alignment sensors and auto-focus sensors (hereafter xe2x80x9cAF sensorsxe2x80x9d) which generate heat, albeit in very small amounts; and in addition, the wafer stage 261 comprises a driving motor, tilt mechanism, and other heat-generating members. Further, the two-dimensional position of the wafer stage 261 is continuously measured with high accuracy by a laser interferometer, not shown. Consequently, if supplying temperature-adjusted air from only a single blower unit 265 (blower outlet) as in conventional devices, fluctuations occur in the air due to temperature irregularities occurring in the lower part of the projection optical system 264 and in the upper part of the wafer 262, so that errors occur in the measurement values of alignment sensors and AF sensors, and errors may also occur in the position of the wafer stage 261 measured by the laser interferometer. And, as a result of these air fluctuations the precision of control of the wafer temperature may be reduced, and expansion or contraction of the wafer may cause magnification errors in the transferred image.
In order to reduce such temperature irregularities, an exposure apparatus has been proposed in which a partial air-conditioning mechanism is mounted to perform partial air conditioning for alignment sensors and AF sensors; but in this case, the temperature differences between the plurality of partial air-conditioning mechanisms may cause further errors.
In recent projection optical systems, numerical apertures are larger and working distances are shorter in order to raise the resolution, so that it is becoming difficult to accurately control the temperature in the vicinity of the exposed area on the wafer.
In view of these points, a first object of this invention is to provide an exposure method capable of detecting with high accuracy defocusing amounts on the surface of a substrate for exposure with respect to the image plane of a projection optical system, even during exposure, and without greatly lowering throughput.
A second object of this invention is to provide an exposure method capable of exposing the image of a mask pattern on a substrate, with the surface of the substrate in for exposure aligned with high accuracy with the image plane of a projection optical system (with the image focused on the substrate), without greatly lowering throughput.
A third object of this invention is to provide an exposure method which, when performing exposure while focusing by an auto-focus method using an oblique-incidence type focus position detection system (AF sensor) which detects the focus position of a surface for detection without passing through the projection optical system, is capable of correcting the drift amount in measured values of the focus position detection system itself, without greatly lowering throughput.
A fourth object of this invention is to provide an exposure method which can separate midway the optical system from the exposure light source to the exposure main unit, and in addition can improve the overall airtightness of the optical path of the exposure beam (exposure light) in the optical system.
A fifth object of this invention is to provide an exposure method which can improve the airtightness of the optical path of the exposure beam in the optical system from the exposure light source to the exposure main unit, and in addition can accurately control the mask temperature.
A sixth object of this invention is to provide an exposure method which, when using an interferometer to measure the position of the substrate stage, can control with high precision the temperature of both the optical path of the interferometer measurement beam, and of the substrate for exposure.
A seventh object of this invention is to provide an exposure method which can control with high precision the temperature of the substrate for exposure, even when using a projection optical system with a short working distance.
A further object of this invention is to provide an exposure apparatus capable of implementing such exposure methods; a method for manufacturing such exposure apparatus; and a device manufacturing method which uses such exposure methods to manufacture devices with high precision.
The first exposure method of this invention is an exposure method in which the image of the pattern of a mask 12 is projected onto a substrate 7 on a substrate stage 2 via a projection optical system 11; which uses a first focus position detection system 117a, 118a which, by irradiating with a detection beam which is oblique to the optical axis of the projection optical system a first set of a plurality of measurement points F1a to F1k on the surface for detection of the object plane side or of the image plane side of the projection optical system, individually detects the focus positions which are the positions in the optical axis direction of this plurality of measurement points; which uses a second focus position detection system 117b, 118b which, by irradiating with a detection beam which is oblique to the optical axis of the projection optical system a second set of a plurality of measurement points F2a to F2k on the surface for detection, individually detects the focus positions at the second set of the plurality of measurement points; in which the first set of a plurality of measurement points and the second set of a plurality of measurement points substantially have at least some measurement points (F1d, F1f, F1i) in common; in which the first and second focus position detection systems are used to detect the focus positions of the measurement points which both have in common, and based on the detection results calibration of the detection results of the first and second focus position detection systems is performed; and in which the detection results of at least one of the first or the second focus position detection systems are used to perform focusing of the image plane of the projection optical system on the surface of the substrate.
By means of this invention, the oblique-incidence type first or second focus position detection systems can be used to measure the focus position of the substrate 7 continuously even during exposure of the substrate or of the fluctuations in the focus position of the mask 12; and based on this measurement value, an auto-focus method (which may include an auto-leveling method) can for example be used to align (focus) the surface of the substrate with the image plane of the projection optical system. Further, by effectively mounting almost all the parts of the first focus position detection system and almost all the parts of the second focus position detection system on different support bases, it is expected that drift and other detection errors in the measurement values of these focus position detection systems themselves will occur independently of each other.
When for example the substrate (wafer or similar) is being changed, and a member holding the prescribed reference plane in the exposure area of the projection optical system is moved, by measuring the focus positions at measurement points which are common and comparing the measurement results, the measurement error of the first and second focus position detection systems themselves can be determined, with hardly any decrease in throughput; and this measurement error can be used to perform calibration of the detection results of the focus position detection systems. After this, the defocusing amount at the substrate surface can be detected with high precision. Even if the support base is the same, the mounting of the optical members is different, so that a similar effect is obtained with respect to fluctuations of these parts.
Here it is desirable that the first and second focus position detection systems irradiate the vicinity of the common measurement points with detection beams which vibrate in mutually different directions, and detect the reflected light of these detection beams. By thus vibrating detection beams in mutually different directions, and by for example synchronously rectifying the photoelectric converted signals of the light reflected from the surface for detection, if the defocusing amounts detected by the first and second focus position detection systems are respectively xcex94fd1 and xcex94fd2, then (xcex94fd1+xcex94fd2)/2 approximately corresponds to the amount of change from the actual focus position (the defocusing amount) of the surface for detection, and (xcex94fd1xe2x88x9266 fd2)/2 approximately corresponds to the detection error (or its absolute value) of the first and second focus position detection systems themselves. That is, the defocusing amount of the surface for detection, and the detection errors (for example, drift amounts accompanying thermal deformation in the optical system) of the focus position detection systems themselves, can be accurately separated.
In this case, it is desirable that a third focus position detection system 8, 9, 17 also be used which detects the focus state of the mask and the substrate by detecting at least one among the first mark 100 on the mask 12 or the second mark on the substrate stage 2, 3 through the projection optical system 11. When the first and second focus position detection systems are used to detect the focus positions at the measurement points common to both, if the difference in the detection results is in a prescribed state (for example, larger than a prescribed value), this third focus position detection system is used to detect the focus state of the mask and substrate, and based on the detection results, calibration of the detection results of the first and second focus position detection systems is performed.
This third focus position detection system can use the TTR (through-the-reticle) method to directly detect with high precision the focus state of the projection optical system, and for example the defocusing amount of the substrate surface with respect to the image plane of the projection optical system; but if it is used frequently, throughput declines. However, in this invention this third focus position detection system is used to perform calibration when, for example, the difference in the detection results of the first and second focus position detection systems is large, so that there is not so great a decline in throughput.
The first exposure apparatus of this invention is an exposure apparatus having a projection optical system 11 which projects the image of the pattern of a mask 12 onto a substrate 7, and a substrate stage 2 which positions the substrate in a plane substantially perpendicular to the optical axis of the projection optical system, and provided with a focusing stage 3, which drives at least one of the mask or the substrate along the optical axis of the projection optical system; a first focus position detection system 117a, 118a which, by irradiating with a detection beam which is oblique to the optical axis of the projection optical system a first set of a plurality of measurement points F1a to F1k on the surface for detection of the object plane side or of the image plane side of the projection optical system, individually detects the focus positions which are the positions in the optical axis direction of this plurality of measurement points; and, a second focus position detection system 117b, 118b which, by irradiating with a detection beam which is oblique to the optical axis a second set of a plurality of measurement points F2a to F2k on the surface for detection, at least part of which are in common with the first set of plurality of measurement points, individually detects the focus positions at this plurality of measurement points; and in which focusing of the image plane of the projection optical system is performed on the surface of the substrate by driving the focusing stage based on the detection results of at least one of the first or the second focus position detection systems. By means of this invention, the first exposure in method of this invention can be used.
In this case, it is desirable that there be provided a third focus position detection system 8-10, 17, which detects the focus state of the mask and its substrate by detecting, via the projection optical system, at least one of a first mark on the mask, or a second mark on the substrate stage; and, a control system 110 to perform calibration of the detection results of the first and second focus position detection systems, based on the detection results of this third focus position detection system.
It is desirable that the first and second focus position detection systems have a light transmission unit to irradiate the vicinity of measurements points each have in common with detection beams vibrated in mutually different directions; light receiving systems to detect the reflected light of this detection light; and detection systems to synchronously detect the detection signals from the light receiving systems, in sync with the vibrations of the detection beams. It is desirable that these two focus position detection systems are manufactured fixed in place on mutually independent support bases, such that measurement value drift does not occur simultaneously.
However, in cases when for structural reasons it is not easy to fix these systems on mutually independent support bases, they can be manufactured such that they are fixed in place on a common support base, and, as one example, a vibrating mirror 57 in the light transmission systems 117a, 117b of the first and second focus position detector systems can be used in common, providing one set of inverting optical systems (61a, 61b), and a set of inverting optical systems 66a, 66b in these light receiving systems, so that the sign of the drift in the two measurement values which occur is reversed, and the drift can be accurately separated.
A second exposure method of this invention is an exposure method in which an exposure light source 250 which generates an exposure beam and an exposure main unit 300 which holds the mask 208 and the substrate 218 are used to transfer the mask pattern onto the substrate by means of the exposure beam; in which a first illumination system 203, which transmits the exposure beam from the exposure light source, is supported independently of the exposure main unit 300, a second illumination system 204 which guides the exposure beam from the first illumination system to the exposure main unit is fixed to the exposure main unit 300, and in which the optical paths of the exposure beams in the first illumination system and in the second illumination system are substantially sealed.
By means of this invention, the first illumination system and second illumination system, which are provided in the optical system from the exposure light source to the exposure main unit, are each substantially sealed, so that if for example a transmissive gas is supplied in the optical path of the exposure beam in these illumination systems, to supply leaked amounts, the leakage of gas from the boundary (junction) of these illumination systems is extremely small, and the purge efficiency is improved. That is, the effective airtightness of the optical path of the exposure beam in the optical system can be increased, the amount of gas used can be reduced, and operating costs during exposure can be lowered.
One example of a transmissive gas, when the exposure beam is light with a wavelength of 200 nm or longer (KrF excimer laser light or similar), is dry air with the ozone removed. When the exposure beam is light with a wavelength of 200 nm or shorter (ArF excimer laser light, F2 laser light (wavelength 157 nm) or similar), nitrogen gas, helium gas, or any inert gas, broadly defined, can be used; and when the exposure beam is light with a wavelength of 150 nm or shorter, helium gas or another rare gas (inert gas as strictly defined) can be used.
In this case, it is desirable that the incidence plane of the second illumination system be conjugate with the plane of formation of the mask pattern, and that a field stop be placed in this incidence plane. By this means, even if for example there is a slight shift in the optical axes of the first illumination system and the second illumination system due to vibration of the exposure main unit, the position of the illuminated area on the mask, and the illumination distribution therein, do not effectively change, so that the entire image of the mask pattern can be transferred with high precision onto the substrate.
In this case, it is desirable that gas which is transmissive for the exposure beam be supplied independently to the two sealed optical paths, and that temperature-controlled gas be supplied in the vicinity of the mask, substantially in parallel to the surface of pattern formation of the mask. By this means, the precision of temperature control of the mask is improved. Hence even if the mask is illuminated continuously by the exposure beam, temperature increases in the mask are eliminated, and no magnification errors occur.
The second exposure apparatus of this invention is an exposure apparatus having an exposure light source 250 which generates an exposure beam, and an exposure main unit 300 which holds the mask 208 and substrate 218, and in which the mask pattern is transferred onto the substrate by means of the exposure beam; and which is provided with a first illumination system 203, supported independently from the exposure main unit, and which transmits the exposure beam from the exposure light source, and with a second illumination system 204, fixed onto the exposure main unit, and which guides the exposure beam emitted from the first illumination system to the exposure main unit. By means of this exposure apparatus, the second exposure method of this invention can be implemented.
In this case, it is desirable that the plane of incidence of the exposure beam, emitted from the first illumination system, on the second illumination system be conjugate with the plane of pattern formation of the mask, and that a field stop 243 be placed in this incidence plane. If this exposure apparatus is the scanning exposure type, it is desirable that a movable field stop 242 be placed in the emission plane of the first illumination system, in order to prevent exposure of unnecessary parts upon starting and stopping scanning exposure of each shot area on the substrate. Even if this movable field stop is driven, any vibrations occurring at that time are not transmitted to the exposure main unit, and overlap precision and other precision can be kept high.
The third exposure apparatus of this invention is an exposure apparatus comprising a projection optical system 209 which projects an image of the pattern of the mask 208 onto the substrate 218, and a substrate stage 224 which holds and positions the substrate in each of a first and a second direction, mutually orthogonal; and provided with a first interferometer 220X and second interferometer 220Y which detect the positions of the substrate stage in the first and in the second direction, respectively, and with temperature control devices 215, 216 having first, second and third blower outlets 287x, 287y, 287a, which supply temperature-controlled gas to the optical path of the measurement beam of the first interferometer, to the optical path of the measurement beam of the second interferometer, and to the substrate, respectively.
By means of this third exposure apparatus, blower outlets are comprised for the measurement beams and for the substrate, so that even if the members of an auto-focus sensor, alignment sensor or similar are installed, temperature-controlled gas is obstructed by these members hardly at all, and both the optical paths of measurement beams and the exposure area of the substrate can be temperature-controlled with high precision.
Here it is desirable that the first interferometer and the second interferometer be installed on their projection optical systems, have reference mirrors 223X, 223Y which are illuminated by a reference beam, and that the third blower outlet 287a of the temperature control device have a cover member 287b to supply temperature-controlled gas to the reference beam, formed into an extended end part. By this means, the substrate is efficiently cooled.
The fourth exposure apparatus of this invention is an exposure apparatus which transfers the image of the pattern of the mask 208 onto the substrate 218 via a projection optical system 209, and which is provided with a cylindrical retaining member 228 covering the sides of the projection optical system, and temperature-control devices 232A, 232B which supply temperature-controlled gas onto the substrate through the space between the sides of the projection optical system and the retaining member from an aperture 228b provided in part of the retaining member.
By means of this fourth exposure apparatus, temperature-controlled gas is efficiently supplied onto the substrate from the space between the sides of the projection optical system and its retaining member. Hence even when the working distance of the projection optical system is short, and even when alignment sensors or similar are positioned close to the projection optical system, the temperature of the substrate can be controlled with high precision.
Here it is desirable that a coolant to cool the projection optical system be supplied to the inner side of the retaining member. By this means, the temperature of the projection optical system can be controlled with still higher precision.
A first method for manufacturing an exposure apparatus of this invention combines, in a prescribed positional relationship, a projection optical system which projects the image of the pattern of a mask onto a substrate; a substrate stage which positions the substrate within a plane substantially perpendicular to the optical axis of the projection optical system; a focusing stage which drives at least one of the mask or the substrate in the direction of the optical axis of the projection optical system; a first focus position detection system which, by irradiating with a detection beam oblique to the optical axis of the projection optical system a first set of a plurality of measurement points on the surface for detection on the object plane side or on the image plane side of the projection optical system, individually detects the focus positions which are the positions in the optical axis direction of the plurality of measurement points; and a second focus position detection system which, by irradiating with a detection beam oblique to the optical axis a second set of a plurality of measurement points on the surface for detection, at least part of which are substantially common to the first set of plurality of measurement points, individually detects the focus positions at the plurality of measurement points.
A second method for manufacturing an exposure apparatus of this invention combines, in a prescribed positional relationship, an exposure light source which generates an exposure beam; an exposure main unit which holds the mask and substrate; a first illumination system, supported independently from the exposure main unit, which transports the exposure beam from the exposure light source; and a second illumination system, fixed onto the exposure main unit, which guides the exposure beam emitted from the first illumination system to the exposure main unit.
A third method for manufacturing an exposure apparatus of this invention combines, in a prescribed positional relationship, a projection optical system which projects the image of a mask pattern onto a substrate; a substrate stage which holds and positions the substrate in a first and a second direction, mutually intersecting; a first and a second interferometer, which detect the positions in the first and the second directions respectively of the substrate stage; and a temperature control device, having first, second and third blower outlets to supply temperature-controlled gas to the optical path of the measurement beam of the first interferometer, the optical path of the measurement beam of the second interferometer, and onto the substrate, respectively.
A fourth method for manufacturing an exposure apparatus of this invention is a method for manufacturing an exposure apparatus to transfer the image of a mask pattern onto a substrate via a projection optical system, and which combines, in a prescribed positional relationship, a cylindrical retaining member covering the sides of the projection optical system, and a temperature control device which supplies temperature-controlled gas onto the substrate from an aperture provided in part of the retaining member, through the space between the sides of the projection optical system and the retaining member.
A first device manufacturing method of this invention employs the first or the second exposure method of this invention, and includes a process to transfer the mask pattern onto the substrate. By means of this invention, devices can be manufactured with high precision.
The third exposure method of this invention is an exposure method in which the mask is illuminated by an exposure beam, and the substrate is exposed to the above exposure beam via a projection optical system; in which a plurality of measurement points on a surface for detection, either on the object plane side or on the image plane side of the projection optical system, or on both sides, are illuminated by a first beam; a plurality of measurement points on the surface for detection, set in substantially the same positions as at least one of the above plurality of measurement points, are illuminated by a second beam; and, the first and the second beam are used to detect position information for the substrate concerning a prescribed direction along the optical axis of the projection optical system at least one measurement point.
By means of this invention, substrate position information concerning prescribed directions at least one measurement point is detected by the first and second beams, and by comparing the measurement results, the error in the substrate position information can be determined with almost no decline in throughput, the surface of the substrate can be aligned with respect to the image plane of the projection optical system (focused), and the substrate can be exposed to an image of the mask pattern.
The fifth exposure apparatus of this invention is an exposure apparatus in which a mask is illuminated by an exposure beam, and a substrate is exposed to the exposure beam via a projection optical system; and provided with a position detection system in which a first beam illuminates a plurality of measurement points on a surface for detection on at least one of the object plane side or the image plane side of the projection optical system, a second beam illuminates measurement points on the surface for detection, set in substantially the same position as at least one of the above plurality of measurement points, and the first and second beams are used to detect substrate position information concerning prescribed directions along the optical axis of the projection optical system at least one measurement point. By means of this invention, the third exposure method of this invention can be used.
It is desirable that this position detection system be such that the first and second beams be illuminated obliquely to the optical axis of the projection optical system and to the surface for detection, and in mutually different directions.
It is desirable that this position detection system be such that all or at least part of at least one set of plurality of measurement points be set within a prescribed area on the surface for detection to be illuminated by beams.
It is desirable that this position detection system further comprise an adjustment device in which a plurality of measurement points including at least one of the above measurement points be illuminated by the second beam, and based on the substrate position information detected by illumination by at least one of the first or the second beam, the image plane of the projection optical system and the substrate be moved relative to each other.
A second device manufacturing method of this invention employs the fifth exposure apparatus of this invention, and includes a process to transfer the mask pattern onto the substrate. By means of this invention, devices can be manufactured with high precision.